Electrical installations prevention

Another approach has been through the use of explosion-proof electrical installations to provide the energy required to accomplish the mission. This method does not limit the amount of energy, rather its philosophy is if an explosion occurs, to contain that explosion within its heavy wall construction and prevent its propagation to the outside environment. 

Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids... 

Other Ignition Sources Hazardous classification of locations for electrical installations is covered in Articles 500-504 of the National Electrical Code (NEC) (NFPA 70). Proper hazardous classification is essential for safety and for prevention of explosion and fire losses. Class 1 in the NEC is for vapors and gases in the United States, in brief. Division 1 of Class 1 includes those locations where flammable concentrations exist continuously or frequently. Division 2 includes locations where flammable concentrations may exist only in case of accidental escape of vapors or gases, or in case of abnormal operation of equipment. Static electricity, which causes fires and explosions with flammable vapors and gases, is covered later in Sec. 26. Cither ignition sources include friction and impact plus rubbing with rubbing... 

The elimination of ignition sources such as hot surfaces, flames, hot gases, mechanical sparks, electrical installations, static electricity or exothermic reactions, is looked upon as preventive to a limited extent only. In former times this measure was rated secondary. 

Colours play an essential safety role in giving information for use in tbe prevention of accidents, for warning of health hazards, to identify contents of gas cylinders, pipeline and services, the identification and safe use of cables and components in electronic and electrical installations as well as the correct use of fire-fighting equipment. 

When the Electricity at Work Regulations (EWR) tell us to ensure that all systems are constructed so as to prevent danger they do not tell us how to actually do this in a specific situation. However, the lET Regulations tell us precisely how to carry out our electrical work safely in order to meet the statutory requirements of the EWR. In Part 1 of the lET Regulations, at 114, it states the Regulations are non-statutory. They may, however, be used in a court of law in evidence to claim compliance with a statutory requirement. If your electrical installation work meets the requirements of the lET Regulations, you will also meet the requirements of EWR. 

Enclosure for electrical installations. Electrical installations in a vault, room, closet or in an area surrounded by a wall, screen, or fence, access to which is controlled by lock and key or other equivalent means, are considered to be accessible to qualified persons only. A wall, screen, or fence less than 8 feet (2.44 m) in height is not considered adequate to prevent access unless it has other features that provide... 

Fire prevention and protection Electrical installations Pipelines... 

Electrical installations are usually tested on completion and before commissioning, but large installations may be tested and commissioned in sections as each part is completed. Subsequently, they need periodic retesting as part of the maintenance procedure to detect incipient faults and to prevent the development of fault combinations that may lead to danger. 

A planned maintenance system comprises a procedure for the inspection, test and repair of the electrical installation and connected apparatus to avoid breakdowns and dangerous faults. It is most commonly regarded as a preventive surveillance system whereby apparatus is inspected and if necessary tested and repaired before it is likely to break down or develop a dangerous fault. The relative contributions of visual examinations and testing have already been considered elsewhere in this book. 

The Guidance Notes on the Electricity at Work Regulations advise that this regulation is concerned with the need for maintenance to ensure the safety of the system and not the actual doing of maintenance in a safe manner. The regular inspection of equipment including the electrical installation is an essential part of any preventative maintenance programme. 

Install flame arresters on atmospheric vents to prevent fire on the outside of the tank from propagating back into the vapor space inside the tank. Provide fire resistant insulation for critical vessels, piping, outlet valves on tanks, valve actuators, instruments lines, and key electrical facilities. Provide remote controlled, automatic, and fire-actuated valves to stop loss of tank contents during an emergency provide fire protection to these valves. Valves should be close-coupled to the tank, and must be resistant to corrosion or other deleterious effects of spilled fluids. Vessels should be provided with overpressure relief protection. 

Heat exchangers with flowing cold electrolyte in fresh-water heat pump reservoirs must be treated similarly [9]. Here the cold electrolyte circuit need not have expensive insulated bushings installed as shown in Fig. 20-3, and the entire water pump equipment does not have to be grounded but must be covered to prevent contact. Electrical separation as in Fig. 20-3 is only undertaken with hot-water heat exchangers. 

Space heaters, particularly in electrical motors and generators which may be idle for significant periods of time, can also help prevent the accumulation of moisture. Space heaters installed in classified areas must operate at temperatures below high temperature devices. 

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